1. Field of the Invention
The invention relates to the fields of optocoupler electrical isolation and self-testing, and in particular, to a method and arrangement for optocoupler self-testing.
2. Background Information
In many applications, such as in medical or process control equipment, electrical isolation is required for all I/O (Input/Output) signals to and from associated processing equipment. Commonly optocoupler devices are used to achieve the desired electrical isolation levels in these applications.
An optocoupler typically consists of a gallium arsenide infrared emitting diode optically coupled with a silicon phototransistor in a dual in-line package. Such devices may typically have a value on the order of 2500 volts per minute of isolation between input and output pins.
An issue that often arises with optocoupler circuitry is testability. Conventionally, these devices cannot be functionally tested on-line without violating the electrical isolation barrier, a significant drawback adversely affecting circuit reliability and/or compromising isolation requirements.